chore(conf): mv some default val of vmargs to emqx_conf

apps/emqx/etc/emqx_cloud/vm.args

@@ -10,13 +10,16 @@
 ## such as `node.name` for `-name` and `node.cooke` for `-setcookie`.
 
 ## Sets the maximum number of simultaneously existing processes for this system.
-+P 2097152
+## Preferably set in `emqx.conf`,
+#+P 2097152
 
 ## Sets the maximum number of simultaneously existing ports for this system.
-+Q 1048576
+## Preferably set in `emqx.conf`,
+#+Q 1048576
 
 ## Sets the maximum number of ETS tables
-+e 262144
+## Preferably set in `emqx.conf`,
+#+e 262144
 
 ## Sets the maximum number of atoms the virtual machine can handle.
 #+t 1048576
@@ -51,6 +54,7 @@
 -kernel net_ticktime 120
 
 ## Sets the distribution buffer busy limit (dist_buf_busy_limit).
+## Preferably set in `emqx.conf`,
 #+zdbbl 8192
 
 ## Sets default scheduler hint for port parallelism.

apps/emqx_conf/i18n/emqx_conf_schema.conf

@@ -13,8 +13,14 @@ emqx_conf_schema {
 
   process_limit {
     desc {
-      en: """Maximum number of simultaneously existing processes for this Erlang system."""
+      en: """Maximum number of simultaneously existing processes for this Erlang system.
-      zh: """Erlang系统同时存在的最大进程数。"""
+The actual maximum chosen may be much larger than the Number passed.
+For more information, see: https://www.erlang.org/doc/man/erl.html
+          """
+      zh: """Erlang系统同时存在的最大进程数。
+实际选择的最大值可能比设置的数字大得多。
+参考: https://www.erlang.org/doc/man/erl.html
+          """
     }
     label {
       en: "Erlang Process Limit"
@@ -24,8 +30,14 @@ emqx_conf_schema {
 
   max_ports {
     desc {
-      en: """Maximum number of simultaneously existing ports for this Erlang system."""
+      en: """Maximum number of simultaneously existing ports for this Erlang system.
-      zh: """Erlang系统同时存在的最大端口数。"""
+The actual maximum chosen may be much larger than the Number passed.
+For more information, see: https://www.erlang.org/doc/man/erl.html
+          """
+      zh: """Erlang系统同时存在的最大端口数。
+实际选择的最大值可能比设置的数字大得多。
+参考: https://www.erlang.org/doc/man/erl.html
+          """
     }
     label {
       en: "Erlang Port Limit"

apps/emqx_conf/src/emqx_conf_schema.erl

@@ -419,7 +419,9 @@ fields("node") ->
                 range(1024, 134217727),
                 #{
                     mapping => "vm_args.+P",
-                    desc => ?DESC(process_limit)
+                    desc => ?DESC(process_limit),
+                    default => 2097152,
+                    'readOnly' => true
                 }
             )},
         {"max_ports",
@@ -427,7 +429,9 @@ fields("node") ->
                 range(1024, 134217727),
                 #{
                     mapping => "vm_args.+Q",
-                    desc => ?DESC(max_ports)
+                    desc => ?DESC(max_ports),
+                    default => 1048576,
+                    'readOnly' => true
                 }
             )},
         {"dist_buffer_size",
@@ -435,7 +439,9 @@ fields("node") ->
                 range(1, 2097151),
                 #{
                     mapping => "vm_args.+zdbbl",
-                    desc => ?DESC(dist_buffer_size)
+                    desc => ?DESC(dist_buffer_size),
+                    default => 8192,
+                    'readOnly' => true
                 }
             )},
         {"max_ets_tables",
@@ -443,7 +449,9 @@ fields("node") ->
                 pos_integer(),
                 #{
                     mapping => "vm_args.+e",
-                    desc => ?DESC(max_ets_tables)
+                    desc => ?DESC(max_ets_tables),
+                    default => 262144,
+                    'readOnly' => true
                 }
             )},
         {"data_dir",